Requirements for Designing a Campus Cluster

When designing your campus cluster, all of the requirements for a standard cluster
still apply. Plan your cluster to eliminate any single point of failure in
nodes, cluster interconnect, data storage, and public network. Just as in the standard
cluster, a campus cluster requires redundant connections and switches. Disk multipathing helps ensure that
each node can access each shared storage device. These concerns are universal for
Oracle Solaris Cluster.

After you have a valid cluster plan, follow the requirements in this section
to ensure a correct campus cluster. To achieve maximum benefits from your campus
cluster, consider implementing the Guidelines for Designing a Campus Cluster.

Note - This chapter describes ways to design your campus cluster using fully tested and
supported hardware components and transport technologies. You can also design your campus cluster
according to Oracle Solaris Cluster's specification, regardless of the components used.

To build a specifications-based campus cluster, contact your Oracle representative, who will assist
you with the design and implementation of your specific configuration. This process ensures that
the configuration that you implement complies with the specification guidelines, is interoperable, and
is supportable.

Connecting to Storage

A campus cluster must include at least two rooms using two independent SANs
to connect to the shared storage. See Figure 7-1 for an illustration of
this configuration.

If you are using Oracle Real Application Clusters (RAC), all nodes that support Oracle
RAC must be fully connected to the shared storage devices. Also, all rooms
of a specifications-based campus cluster must be fully connected to the shared storage
devices.

Sharing Data Storage

Your campus cluster must use SAN-supported storage devices for shared storage. When planning
the cluster, ensure that it adheres to the SAN requirements for all storage
connections. See the SAN Solutions documentation site for information about SAN requirements.

Oracle Solaris Cluster software supports two methods of data replication: host-based replication and
storage-based replication. Host-based data replication can mirror a campus cluster's shared data. If
one room of the cluster is lost, another room must be able to
provide access to the data. Therefore, mirroring between shared disks must always be
performed across rooms, rather than within rooms. Both copies of the data should
never be located in a single room. Host-based data replication can be a
less expensive solution because it uses locally-attached disks and does not require special
storage arrays.

An alternative to host-based replication is storage-based replication, which moves the work of
data replication off the cluster nodes and onto the storage device. Storage-based data
replication can simplify the infrastructure required, which can be useful in campus cluster
configurations.

For more information on both types of data replication and supported software, see
Chapter 4, Data Replication Approaches, in Oracle Solaris Cluster System Administration Guide.

Complying With Quorum Device Requirements

You must use a quorum device for a two-node cluster. For larger
clusters, a quorum device is optional. These are standard cluster requirements.

Note - In Oracle Solaris Cluster 3.3, a quorum device can be a storage
device or a quorum server.

In addition, you can configure quorum devices to ensure that specific rooms can
form a cluster in the event of a failure. For guidelines about
where to locate your quorum device, see Deciding How to Use Quorum Devices.

Replicating Solaris Volume Manager Disksets

If you use Solaris Volume Manager as your volume manager for shared device
groups, carefully plan the distribution of your replicas. In two-room configurations, all disksets
should be configured with an additional replica in the room that houses the
cluster quorum device.

For example, in three-room two-node configurations, a single room houses both the quorum
device and at least one extra disk that is configured in each of
the disksets. Each diskset should have extra replicas in the third room.